The present invention relates to a system and method for rapid weighing and metering of items. More particularly it relates to postage metering systems used to weigh, determine postage for, and meter (i.e. imprint with a postal indicium representative of the postage determined) mail pieces or the like.
Postal scale systems are well known. Such scale systems weigh a mail piece and determine the appropriate postage for that mail piece as a function of the weight. Postal mailing systems where a mail piece is transported onto a postage scale system, the appropriate postage is determined, and the mail piece is then transported to postage metering system for imprinting with a postal indicium representative of the postage determined are also known. One such system is described in U.S. Pat. No. 4,742,878; issued May 10, 1988. In such systems there is a constant need to increase the rate at which the scale can determine the weight of a mail piece in order that the throughput of the system can be increased.
U.S. Pat. No. 4,787,048; issued: Nov. 22, 1988, discloses one approach to decreasing the time required for a postage scale system to determine the weight of a mail piece. The system disclosed in this patent takes advantage of the structure of postage rate charts, i.e., the function that relates the weight of the mail piece to the appropriate postage amount. Such rate charts provide a constant postage value for all weights between a pair of predetermined weight breaks. The system of the '048 patent takes advantage of this by use of an algorithm where a first estimate of the weight is made and used to determine the postage amount unless the first estimate is within a predetermined distance of a break point, in which case a second more accurate estimate is made.
While such systems have proven to be highly satisfactory for their intended purpose a basic problem remains that the weight of each mail piece in batches of mixed weight mail must be determined and the corresponding postage amount calculated before the vault (i.e. secure accounting registers which track postage expended by the meter to assure that the postal service receives payment for all mail pieces metered) can be debited for the postage amount and an appropriate indicium generated. Because of the secure nature of the vault and the complexity of modern digitally printed indicia, which typically use encryption to assure that each indicium is uniquely identified with its mail piece to prevent generation of counterfeit indicia, these processes take a significant amount of time; requiring that the transport be longer than otherwise necessary, or be slowed or stopped, to provide dead time to account for postage amounts expended and to ready an indicium for printing.
Thus it is an object of the present invention to provide a method and system for increasing the average time available to generate indicia and account for postage expended without increasing dead time.